Magnetic phase diagrams of classical triangular and kagome antiferromagnets

Abstract

We investigate the effect of geometrical frustration on theH–T phase diagrams of the classical Heisenberg antiferromagnets on triangular and kagomelattices. The phase diagrams for the two models are obtained from large-scale Monte Carlosimulations. For the kagome antiferromagnet, thermal fluctuations are unable to liftdegeneracy completely and stabilize translationally disordered multipolar phases. We find asubstantial difference in the temperature scales of the order by disorder effect related todifferent degeneracy of the low- and the high-field classical ground states in thekagome antiferromagnet. In the low-field regime, the Kosterlitz–Thouless transitioninto a spin-nematic phase is produced by unbinding of half-quantum vortices.